How Far Should Seedlings Be From Grow Light

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Last Updated on October 29, 2022

Light is one of the most crucial requirements for growing plants indoors. Positioning your grow light in the perfect area is important to ensure your plants get the appropriate grow light quantity. Now, when it comes to seedlings, we would like to know how far seedlings should be from grow light.

Seedlings are fragile and require proper care as they develop. We will be discussing how far should your seedlings be from grow light so they can grow appropriately.

Get To Know How Far Grow Light Should Be From Seedlings

Although a couple of seed varieties require darkness to grow, some plant seedlings do require light for seedlings’ development. The seedling phase is a very fragile phase and they usually require less light intensity. Thus, the distance from your grow light to seedlings should be far enough to reduce light intensity.

Some may think that supplying optimal light to your plants will increase plant growth and yields. This is true, but have in mind that this applies to only matured plants. Your seedlings will be too delicate during this stage, so they will require tender care. When your plants are established, you can go ahead and feed them with optimal light intensity.

Let’s take a look at various types of grow light and how far you should place them from your plants.

LED Grow Seedling Light & Wattage

Generally, you should position your LED to grow light around 24 to 36 inches above the canopy seedlings.

Also, how far you should position your grow lights towards your seedlings will solely depend on the power or wattage of the light bulb. A bulb that is bright and far away from the plant could supply a similar light intensity with a dimmer or low light bulb closer to the plant.

Grow light with lower wattage of around 200 should be positioned between 12 to 20 inches above the plants’ canopy. On the other hand, grow light with higher wattage should be placed 34 to 46 inches from the plants’ canopy.

LED lights release mostly red and blue wavelength, thus there are appropriate for plants early stage such as seedlings. They are also great for the flowering phase and fruiting phase as these stages require more intensive light for optimal yield.

LED Grow Light, Roleadro 75W Grow Light for Indoor Plants Full Spectrum Plant Light for Seedling

Fluorescent Grow Light

Fluorescent growth light comes in 3 types namely T5, T12, and compact fluorescent lamps. The added advantage of using fluorescent grow light is that it rarely causes light burn. This is because it does not produce too much heat. Notwithstanding, ensure you keep a close eye on the light heat and intensity.

Fluorescent growth light should be positioned between 6 to 12 inches for seedlings. For the vegetative and flowering phase, position your grow light between 12 to 16 inches for maximum production.

Other Plant Stages Grow Light Distance

Let’s take a look at other plant stages to grow light distance requirements:

  • Vegetative Phase: the LED grow light distance for the vegetative phase of a plant is between 12 to 24 inches above the plants’ canopy. The light position is closer to the plant because optimal light is required during photosynthesis for rapid plant growth. The light intensity will also help in the development of stronger and healthier stems and roots.
Other Plant Stages Grow Light Distance - Vegetative Phase
  • Flowering Phase: when the vegetative stage is complete and the plant advances into the flowering phase, the light intensity requirements diminish. The distance from the top of the plant to the grow light should be between 18 to 24 inches. In the flowering phase, plants start to grow in height and develop fruits. As your plants grow taller, you can decide to change or not change the distance of the grow light. Usually, if you don’t want your plant to grow too tall, you should leave the grow light distance the same.

Disadvantages Of Too Much Light

As we have pointed out earlier that light is one of the key factors to seedling development, we would also point out what too much light can cause your plants.

If your seedlings receive too much light, it can cause stress to your plant. To know if your plant is taking in too much light, look for any sign of light burns, leave discoloration. Abnormal or stunted growth is another sign to look for.

Once you see these signs, it’s a call for action. Adjust the distance of your grows light accordingly to fix the problem quickly.

Disadvantages Of Too Much Light


How close should I keep my seedlings to their grow lights?

 If you are in a spot with good sunlight, then you may be able to get away with having them closer. I would say that if they are on a tray, then you should be able to get away with putting them as close as the tray allows. As far as lighting goes, you will probably need a full spectrum LED grow light. I am not sure what kind you have, but I know that the HID bulbs are really only effective when there is no direct sunlight, otherwise it will not light up.

I'd say at least 18" apart for optimal growth. If you're doing it right, you shouldn't need much more than a 2-3 foot gap, depending on the height of the lights. If they're too close together, you'll be wasting energy and possibly burning your plants.

Does the type of light matter in terms of the distance?

Yes. You'll need to figure out what the light spectrum is that you are growing for. If you're trying to grow plants that are grown for eating then you will need to know how much of the spectrum they are best at consuming.

Then you will need to calculate the amount of light that is needed to provide that amount of light to your plant. For example, if you are growing tomatoes, you would use a combination of red, blue and yellow lights to simulate sunlight. The more red light, the more heat, and the more yellow light, the more light but also more energy. You can get away with less red light if you have enough blue and yellow light. For example, if you had two 5500K fluorescent tubes, one blue and one yellow, it would be able to produce about 1.2 times as much light as a single fluorescent tube of similar wattage. If you had two of the same tubes but they were only 5500K then you could get around twice the amount of light. It's best to figure out what the light spectrum for your plant is going to be before setting up the grow room. You don't want to grow plants in the wrong light spectrum.

Can they be too far apart?

My understanding is that it's not a problem to put the grow lights too far away from the seedlings. However, you may want to get closer so that the light is more diffused and even. It's easier to keep a grow light in a plant than a human. You could also try to use LED grow lights. These are much more energy efficient, and will last a lot longer. 

Conclusion: How Much Light Should Seedlings Get?

How your grow light should be far from seedlings will depend on the type of grow light you’re using and the wattage or light intensity. With the information we have given above, we hope you have learned the right distance to place your grow light from your seedlings.

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